Process for making coating material emulsions



Patented Apr. 8, 1047 PROCESS FOR MAkING COATING MATERIAL EMULSIONSLaszlo Auer, South Orange, N. J.

No Drawing. Application February 19, 1944, Serial No. 523,108

18 Claims.

1 In my British Patents 318,562, 321,692, and 341,490 as well as in myUnited States Patent 2,007,958, I have produced plastic masses out offatty oils by the way of aggregating them in the form of aqueousemulsions. The basic idea of my development program at the time thosepatent applications were filed, was to convert fatty oils into arubber-like stage, having properties similar to natural rubber. Theproducts so obtained could be milled and compounded on rubber mills.

According to the present invention, I have prepared by new meansaggregated fatty oil emulsions for use in protective coatings, such asvarnishes, paints, enamels, etc. The emulsions dealt with in the presentapplication I call "air sensitive emulsions. Under air sensitiveemulsions I understand such emulsions, which are sensitive to the actionof the air, when exposed to it in form of a thin layer, such as a film,e. g. of 0.0015" to 0.003 wet film thickness; insofar as they containthe fatty oils in the form of solid particles and on'the action of theair on their thin layers, as soon as demulsification sets in, they forma solid and coherent film. Such solid film is formed also under suchconditions under which a large percentage of the water, originally beingthe dispersion medium, is still occluded in the film. The film formationis usually reached within a couple of seconds, but latest in a couple ofminutes and always in a shorter time than 30 minutes. The non-fluidstage is reached even earlier. In some exceptional cases it may bedesirable to slow down artificially the film formation of air sensitiveemulsions, so that the film formation should occur within a timeexceeding 30 minutes, however, the film formation is rarely slowed to anextent that it should take more than 1 hour. If an air sensitiveemulsion is rubbed between the fingers for a minute or so, it will alsodeposit solid particles or a solid film in between the fingers.

Briefly considered, the air sensitive emulsion of the present inventionis prepared as an oilin-water emulsion of which the dispersed phaseincorporates a fatty acid ester, such as a fatty oil. The fatty oil ispreliminarily bodied to a relatively heavy viscosity and thenemulsified, and, in dispersed form, the particles of the fatty oil aretreated to effect agglomeration, for instance, by employing hydrogenperoxide, or in other ways as more fully described here below.Advantageously the pH value of the emulsion is retained on the acid sideand within certain limits during the aggregation treatment; The degreeof prebodying and of aggregation of the dispersed particles in situ issuch as to render the emulsion highly sensitive to the action of airwhen spread in thin films and thereby provide for the formation of acoherent solid film immediately upon demulslfication of the emulsion.

To explain the importance of my new emulsions, I want to refer to theknown facts that if drying oils are used to prepare coating materials,before they form a solid film, they undergo a comparatively slow dryingprocess. form a solid film, they remain for a long period in a liquidstage and reach the so-called dustfree" stage after a considerable lapseof time. This property of drying oils is causing limitations in theiruse in protective and decorative coatings and in cases where rapiddrying is needed it was necessary to use lacquers, such asnitro-cellulose lacquers. Such lacquers contain more expensivefilm-forming solids than drying oils and their solvents are also moreexpensive than those used in connection with dryin oils. Now, my newemulsions enable the formulation of very fast drying, almostlacquer-like drying, coating materials, while using as principalfilmforming solids drying and semi-drying oils, and

utilizing water as principal dispersing agent.

It is old in the art to make emulsion paints, which contain drying oilsand drying oil emulsions have been used.for many diversified purposes inthe past. However, my present invention does not deal with emulsions ofdrying oils in general, but with quite specific types of emulsions,containing drying oils or semi-drying oils. The dispersed phase of myemulsions has been aggregated and the emulsions possess qualitiesdefined further above as inherent to air sensi tive emulsions.

Many investigators consider the process I am calling as aggregation, aspolymerization, but I am confident of the fact that actually what occursin the emulsion is better defined with the expression used by me, thatis, by aggregation. (See article "Polymerization or Aggregation?-National Paint Bulletin, October, 1937.)

Before they aciaess STARTING MATERIALS The process may be applied tofatty oils generally, including drying oils, semi-drying oils, andnon-drying oils. A typical list of such oils follows:

Tung oil Oiticica oil Dehydrated castor oil Linseed oil Perilla oilSunflower oil Poppyseed oil Soya bean oil Walnut 011 Rapeseed oilPineseed oil Olive oil Corn oil Cottonseed oil Coconut oil Babassu oilHydroxylated oils such as castor oil, etc. Fish oils (train oils) Itshould be noted that, in addition to the natural glycerin esters of thefatty acids, other esters may be employed, such as synthetic glycerinesters of fatty acids, and fatty acid esters formed with otherpolyhydric alcohols, such as glycols, pentaerythritol, mannitol,sorbitol, etc. In short, natural or synthetic oils may be used, whetherof animal or vegetable origin, as well as fractions of either type.

For convenience, all such materials and combinations are referred toherein merely as fatty oils.

As the reaction taking place in my process is a reaction of thepolyhydric alcohol esters of unsaturated fatty acids, all such mixedester type synthetic resins may be used as starting materials for myprocess, which comprise at least 50% unsaturated fatty acid esters,calculating such portion of the polyhydric alcohol radical into theester, which is needed to form the esters with the unsaturated fattyacid content of the synthetic resin. Such synthetic resins are, forinstance,

the alkyd resins of the kind which are mixed esters of polycarboxylicacids and unsaturated fatty acids.

Examples of polycarboxylic acids, forming alkyd resins useful in myprocess are for instance:

Phthalic acid, Maleic acid, Succinic acid, Malic acid, Tartaric acid,Fumaric acid, Citric acid, Adipic acid, Sebacic acid, Azelaic acid,Suberic acid, etc., or Anhydrides of such acids.

Examples of the unsaturated fatty acids, forming alkyd resins useful inmy process are for instance:

Linseed oil fatty acids,

China-wood oil fatty acids,

Perilla oil fatty acids,

Oiticica oil fatty acids, Dehydrated castor oil fatty acids, Sunfloweroil fatty acids,

Soyabean oil fatty acids, Cottonseed oil fatty acids,

Corn oil fatty acids,

Fatty acids of fish-oils (train oils).

The polyhydric alcohols, forming the esters useful as starting materialsin this process, should be preferably at least tri-hydric, such asglycerine.

For the purposes of this specification under fatty acid esters Iunderstand polyhydric alcohol esters of acids of fatty oils, whichesters contain in their acid component at least 50% acids of fatty oilsand which fatty oil acids comprise fatty acids having at least twodouble bonds. In this definition of fatty acid esters, there is includedthe group of drying and semi-drying fatty oils, further the group ofsynthetic oils and the group of alkyd resins, not containing more than50% polybasic acids in their acid component,

Any appropriate mixtures or combinations of members of the abovedescribed classes may be treated, as desired.

The better drying a fatty oil is, the more suitable it is for my presentprocess. I found that at 0 least some of the fatty acids present in myoils should preferably contain more than one double bond 'in themolecule. This includes esters of the drying oil fatty acids and of thesemi-drying oil fatty acids. I also foundthat esters of fatty acidshaving conjugated double bonds undergo easier my emulsion aggregationprocess, than fatty acids with isolated double bonds.

I found that the fatty oils here above described are suitable to myemulsion aggregation only if they have at least a certain criticalminimum viscosity or body. In other words, to be susceptible to theaggregation in aqueous emulsion, they have to be pro-bodied by the usualmeans, known in the art. Such bodying may be carried out for instance byheating the oil to heat-body temperatures, or by blowing the oil with agas, such as air or oxygen at room or elevated temperatures. Other meansof bodying are treatment with ultraviolet light, by exposure to anelectric field, etc.

I found that my oils have to have a minimum viscosity of Q in theGardner scale, but preferably they should have still higher viscosities,such as V or Z-I on the Gardner scale, and I further found that if theviscosity is more than 2-6, my emulsion aggregation reaction is stilleasier to perform.

However, drying oils are used in coating materials not only as such, butalso in a blended form together with natural and synthetic resins.

The natural and synthetic resins, useful in my present process, areknown in the art as varnish resins and all of them are soluble directly,or after a suitable treatment in varnish oils.

As resin components of my air sensitive emulsions I may use many of thenatural and synthetic resins, of which the following list are examples:

Rosin,

Esters of rosin with polyhydric alcohols, (glycerine, glycols,pentaerythritol, sorbitol, mannitol, etc.)

Congo,

Congo esters,

Other copals (e. g. kauri) Cumar and indene resins,

Maleic anhydride-rosin-polyhydric alcohol, type maleic resins,

Rosin modified phenolic resins,

So-called pure phenolic resins,

Terpene resins, etc.

In case oil-resin blends are used as the dispersed phase of myemulsions, the oils and resins may be advantageously cooked together inthe regular way as varnish solids are prepared in the varnish kettle. Ifin such a case unbodied oils are used as starting-material, it isdifficult to establish what the viscosity of the oil is in the varnishcook, as the oil could not regularly be separated from the resin withwhich it forms a uniform blend. In such a case we measure the viscosityof the oil-resin mixture and because such mixture may frequently be tooviscous to be measured directly in the Gardner scale, when we refer tothe viscosity of the blend, we may have to express same related to asolution of the blend in question in an organic solvent, such as forinstance, in mineral spirits, giving also the solid content of such asolution.

As a general observation, I may mention that fatty oils form morereadily air sensitive emulsions in presence of resins, than in absenceof resins. In other words, if we compare cooks at the same temperatureand for gradually progressing times of cooking, we find that cooks inwhich resins are present, form earlier air sensitive emulsions, underotherwise comparative conditions, than fatty oils alone in absence ofresins. This statement is meant to apply for such cases in whichemulsions of various cooking times are compared and checked whetherunder comparative reaction conditions they could be aggregated to thestate in which they yield air sensitive emulsions. The resin containingcooks can be converted into air sensitive emulsions with a shortercooking time than the resin-free comparative oil cooks.

TREATMENT CONDITIONS Bonxmc The first step in my process is, asindicated above, the bodying of the oil. This is effected. in any ofseveral known ways, such as:

1. By heating the oil, at suitable bodying temperatures, above 200 (3.,and usually above 250 (2., until the desired viscosity is attained. a(Stand oils, polymerized oils, or heat bodied oils.)

2. By blowing air, oxygen or ozone over or through the oil to bethickened, either at room temperatures or at elevated temperatures.(Oxidizcd oils or air blown oils.)

3. By utilizing various gases, such as S02, HzS, CO2, N2, etc. either toblanket the oils during heat treatment or to treat the oils directly byblowing or bubbling the gas through the oil, either with or without theuse of heat. (Nonoxidized bodied oils.)

4. By treating the oil with ultra-violet rays. (Uviol oils.)

5. By treating the oil in an electrical circuit with a potentialdifference capable of yielding bodyin (Voltol oils).

6. By bodying oils with modifying agents (polar compounds) as disclosedin my U. S. Patents Nos. 2,189,772; 2,213,944; 2,293,038; 2,298,270;2,298,- 916; etc., and the various divisions and continuations thereof.

7. By heat-bodying under vacuum, occasionally coupled with asteamtreatment to distill off free fatty acids.

Combinations of certain of these bodying techniques may be employed, as,for example, bodying with polar compounds in the presenceof anelectro-static field.

It is important to the attainment of best results that the oil should bebodied before emulsifying it and treating it in the emulsion inaccordance with my invention. Even where the bodying is relativelyslight some advantages may be realized, but the strikingly improvedresults of my preferred method are most readily produced if the oil isquite heavily bodied. The ex- 6 tent or degree of bodying may vary overa considerable range, depending upon the purposes in view. However, inone preferred practice of the invention, the range of bodying desirablebefore emulsion aggregation may be defined by limits, as follows:

In the first place, the oil should be bodied at least to a degree suchthat when heated to' 160 C. with l sulfur an irreversible gel will formwithin about 4 hours and most desirably within about 3 hours.

On the other hand, the oil preferably should not have a body heavierthan that which would result in conversion to an irreversible gel inless than 15 minutes when vulcanized with sulfur at 120 C.

It may be mentioned that these limits, as just defined, are applicablenot only to emulsionaggregation treatment of fatty oils themselves butalso to similar treatment of fatty oils in admixture with resins,thereby yielding emulsion- 1aggregated varnish solids of theoleo-resinous I prefer to define the desired viscosity as abovedescribed, because, in the light of present knowledge, it is easier toapply some such test than it is to separate the component parts of anoleoresinous mixture in order to determine the viscosity of the oilalone.

In addition to the foregoing limits of the range of bodying, it may bementioned that alternatively the preferable range of bodying of the oilmay be expressed by any suitable viscosity scale. Thus, e. g., fornatural oils a satisfactory range of bodying is from about 15 to 20poises (Y on the Gardner szale) up to in the neighborhood of 800 poises(beyond the upper limit of the Gardner scale). For most purposes it willbe found desirable to utilize a viscosity upwards of about poises. Themeasurement of the desired body by viscosity scales will, of course, bebest suited'to the situation where the oil is bodied prior to admixturewith a resin, as in the preparation of varnish bases.

The best viscosity for any particular oil or oleo-resinous mixture willbe a function of several variables. To mention a few, the solid'contentand pH of the emulsion used, the temperature of treatment, the type ofresin used, if any, the nature of the oil, the proportion of oil toresin, the effect desired, etc., will influence the degree of body to beemployed. In each individual case, however, it is easy to determine themost favorable viscosity to use. After the proper viscosity has beendetermined, the desired conditions can readily be duplicated. Forinstance, one may simply note the appearance and the behavior of so muchof the material as clings to the stirring paddle when it is lifted outof the kettle from time to time, such as flow and the lengths-of thestring formed, etc. I

It should be remembered, of course, that different resins have diverseeffects on the oil bodying. Allowances must be made for this fact incalculating the time necessary to attain proper bodying of a particularmixture, and it should also be realizedthat in a certain case it may bepossible to proceed to the emulsion-aggregation treatment step beforetheviscosity of the mixture is as high as would be necessary in anothercase with a different oleo-resinous mix.

A further convenient method establishing the necessary critical minimumviscosity of my fatty acid esters is the ammonia test. The testcomprises in immersing a small pill of the ester by 7 the aid of a glassrod into concentrated ammonium hydroxide solution kept in a test tube.Satisfactory viscosity is reached if the pill solidities in theconcentrated ammonia in not more than minutes to such an extent thatwhen pressed against the wall of the test tube by the glass rod, itshould feel rubbery (elastic), dry and should not stick to the wall ofthe test tube.

The ammonia test ls particularly suitable to determine the necessarycritical viscosity limit in the case of oil-resin mixtures or in thecase of alkyd resins, which very often'do not have a ready flow at roomtemperature. Alkyd resins, as it is known, are very viscous andoftenform plastic solids at room temperature, if the polybasic acid contentis considerable.

It should be mentioned that generally speaking esters containing fattyacids with conjugated double bonds have a lower critical minimumviscosity requirement from point of view of the emulsion aggregationprocess, than similar esters with isolated double bonds.

Accuses-non Paocsss As described further above, it is a prerequisite tomy process that the oils should have at least a certain critical minimumviscosity. If they reach that minimum viscosity, they may undergo theemulsion aggregation process.

My aggregating agent is oxygen. I believe that the active agent of myprocess is an electrically charged oxygen particle. However, I have nodefinite proof of that supposition. As not any and all oxygen may act inmy process as aggregating agent, I shall refer to the oiwgen which issuitable in m process as "active oxygen and I believe that the particlesof this active oxyge are most probably electrically charged.

In my eo-pending applications, Serial No. 521,441, filed February 7,1944, and Serial No. 522,803, filed February 1'7, 1944, I have describedseveral means how to obtain my active oxygen. These co-pendingapplications deal with a somewhat related subject matter.

I can obtain my active oxygen in various ways.

' (1) I may use a peroxide, such as a metal peroxide or hydrogenperoxide, or an organic peroxide to supply my active oxygen to myemulsions. (2) I may blow oxygen or an oxygen containing gas, such asair, through my emulsions. (3) I may use the oxygen which is present inthe water phase of my emulsion as adsorbed oxygen.

However, as the three kinds of oxygen above referred to do not act withequal velocity, auxiliary assistance may be needed in many of the cases.

I found for instance that the application of heat is accelerating theaction of my aggregating agent (active oxygen). In fact, the applicationof heat is one of the roads which lead to activate the oxygen particlesin my reaction. Temperatures above room temperature may be used for suchactivation and they should not exceed the boiling point of the emulsionto be treated. Usually temperatures between 50 C. and 80 C.

e useful, but temperatures below 50 C. and a ove 80 C. may also be used,if other reaction conditions warrant such a procedure, but suchtemperatures should not exceed the boiling point of the aqueousdispersion.

Agitation of the emulsion also acts as an activating factor and it mayadvantageously be combined with the application of temperatures higherthan room temperature. It is believed that the oxygen particles whichare adsorbed in be used in connection with blowing air or oxygen theaqueous phase of the emulsion may obtain electric charges by friction,caused by forced movement. Elevated temperatures themselves areincreasing the movement of air particles adsorbed in water and agitationcauses also an increase in the movement of adsorbed gas particles. Thecombination of agitation and heat causes increased and combinedactivation.

Another way to activate the adsorbed oxygen is by treating the emulsionwith energy being in the form or radiating energy of various wavelengths, such as ultra-violet light, X-rays, etc., which are known toionize air.

The application of vacuum, that is reducing the pressure over theemulsion, accelerates the emulsion aggregation process and helps toactivate the oxygen particles present.

In case peroxidesare used and oxygen is liberated in situ, furtheractivation by agitation and/or heat is not anecessary requirement andthe aggregation may be carried out in a satisfactory way, at roomtemperature and even at temperatures lower than room temperature. Incase, however, only the oxygen present by natural adsorption in theaqueous phase is used for the aggregation process, it is necessary toactivate same and temperatures higher than room temperature andpreferably agitation are needed to complete the reaction withinpractically useful time intervals.

If blowing of air 31' oxygen through the emulsion is used as a source ofthe aggregating active oxygen, the conditions are usually in-between theabove-mentioned two extremes, on one end of using peroxides and on theother end of using the oxygen adsorbed in the Water as sole aggregatingagent. Whether heat and agitation should through the emulsion, maydepend on the particular reaction conditions involved, on the finenessof sub-dividing the gas bubbles used, the body and nature of the oil oroil-resin mixture, amongst others. It may be mentioned as a generalrule, however, that under otherwise equal conditions peroxides actfastest, blowing of air or oxygen is next fast, and using the adsorbedoxygen only, is the slowest of the three alternatives. Further, it maybe stated that under any condition agitation and/or heat accelerate theaction of the oxygen and that their use is essential only in the slowestrange.

With regard to the quality of the film-forming solids, the films whichhavebeen produced by the smallest possible quantity of active oxygen aremost desirable, as they contain very little chemical oxidation products,whereas in cases where peroxides are used in considerable proportions,the active oxygen may cause chemical oxidation, yielding by-products,which are in many cases undesirable components of film obtained fromcoating can; :.;;.1ons.

CRITICAL HYDROGEN ION CONCENTRATION One of the important criterions ofmy process is the pH of the emulsion. I found that it is important tohave critical pH limit to carry out my process satisfactorily.

In my co-pending applications, Serial No. 521,441 and Serial No.522,803, I described various pH ranges to achieve emulsion aggregationof my esters. In the present process I found that special advantagesderive from the fact that the emulsion aggregation process is carriedout on the acid side.

The reaction is greaty accelerated by a pH not exceeding .7. However,for many purposes I found that it is advantageous to have a pH whichdoes not exceed 4, such as for instance a pH of 2.8.

Several advantages may be obtained, if the emulsion aggregation processis carried out according to this invention on the acid side, that is ina pH range below '7.

One advantage is. for instance, that when working on the acid side, thepH ofthe emulsion remains constant and does not drop. This is incontrast to observations made, when the emulsion a gregation is carriedout on the alkaline side. In the latter case the pH drops regularly andit is difiicult to keep the emulsion stable by either adding ingredientsincreasing the pH, and/or by using emulsifying agents which are a tiveboth on the alkaline and on the acid side. Without such precautions theemulsion may easily break. However, if the emulsion aggregation processis carried out according to the present invention on the acid side, thepH remains stable and it is easy to stabil ze the emulsion; Further, theselection of emulsifying agents is also simplified.

A further advantage of the present process is, that the emulsionaggregation may be carried out in absence of driers. It has been foundthat when working on the acid side the addition of driers isunnecessary, In fact driers may retard the emulsion aggregation process,when work ng on the acid side. For many purposes it is advantageous tohave films of .coating materials containing fatty oils, which do notcontain metallic driers. Such films, not containing metallic driers havebetter aging qualities and may be used with advantage as ingredients oflacquer emulsions, or may be mixed with lacquer emulsions, to form newtypes of coatings. Presence of metallic driers causes all kinds ofcomplications in connection with simultaneous use of lacquers and fattyoils. Difficulties here referred to .are well known to those skilled inthe art.

CONCENTRATION OF THE EMULSION I also found that the concentration of myemulsions, to be aggregated, is important and as a general rule lowersolid content will accelerate the reaction, whereas higher solid contentwill retard same. A particularly advantageous range is between and 20%solids. Vehicles of coating materials should preferably have olids inthe neighborhood of 50% or more. It is possible to carry out theemulsion aggregation process in the neighborhood of 50%, or in otherwords, air sensitive emulsions can be produced in emulsions having 50%solids. In fact, even higher solids going up to 70% may be applied.However, the more concentrated emulsions we use, the more acceleratingand activating conditions we have to apply for satisfactory results. Forinstance at a 20% concentration it is easy to apply the reaction usingthe adsorbed oxygen only, as aggregating agent, with comparatively lowtemperatures and slow agitation. However, using higher concentrations itmay become necessary to use peroxides as activating agents and if theconcentration is still further increased, the simultaneous use ofperoxides and heat and agitation may be required to secure thetransformation desired.

It may be advantageous to carry out my process in an emulsion with lowsolid content, to accelerate the process and aft-er the emulsionaggregation is completed, to concentrate the comparatively diluteemulsion. Such concentration may erase OXYGEN Surpmmc Assn-rs Asmentioned further above, if other reaction conditions are proper, theoxygen content of the water, present in the emulsion, may besatisfactory..

Oxygen may be supplied to the emulsion in form of oxygen gas or oxygencontaining gases, such as air, by bubbling through the emulsion suchgases or by introducing them by known means. Ozone may also be used.

To produce oxygen in situ peroxides or other per-compounds may be used.In most of the examples hydrogen peroxide is used to illustrate theaddition of per-compounds. However, other peroxides may also be used,such as sodium peroxide, barium peroxide, magnesium peroxide, zincperoxide, other metal peroxides, or organic peroxides. such as benzoylperoxide, urea peroxide, etc. Examples of per-compounds are furtherperborates, percarbonates, persulfates, such as potassium, sodium andammonium persulfates, perchlorates, pyrophosphate peroxides, ozonides,etc. The criterion of the usefulness of these agents is that they shouldsupply oxygen in situ under the reaction conditions applied in myprocess and that the emulsion could be prepared in such a way that itshould not break intheir presence.

EMuLsIrYmc AGENTS Trade Name and Source Manufacturers DescriptionDupouol ME. E. I. du Pont de Nemours 6: Co.

Aerosol GT. American Cyanarnid Company.

Emulnhnr AG, General Dyestuff Corporation.

Nekal A, General Dyestufi Corporation.

Igepon, General Dyestufl Corporation.

Triton, Rohm & Haas Emulgor A, Glyco Produets..

Wetanol, Glyco Products Darvan #1, R. T. Vanderbilt Company.

Homkem, Homkem Corp Beta Sol, Onyx Oil & Chemical Company. Peitarnul126, Hayden Chemical orp. Pentamul 147, Heyden Chemical Corp.

Fatty alcohol sulphate.

Dioctyl ester of sodium sulphosuccinlc acid. Polyethyleueoxidecondensation product. Sodium salt of alkyl-substituted naphthalenesulphonate. Sodium sulphouale of an oleic acid ester of an aliphaticcompound, for instance, the type of C|7H33CONCH3C:H4SO3NZL Sodium saltof aryl alkyl poly ether sulphonate. A highly polymerized glycol ester.Modified sodium salts of sulphated fatty alcohols. Polymerizcd sodiumsalts of alkyl naphthalene sulphonic ac s. Purified sulpho1iguiu.Quaternary ammonium salt.

Pentaerythrltol monooleate.

Pentacrythrltol mouolaurate.

I found that from the various emulsifying agents, for my presentprocess, such types are most suitable, which are active on the acidside. The non-ionic emulsifying agents belong to that class, such as forinstance, Pentamul 126 and 147, nonaethyleneglycolmonooleate. or thecorresponding dioleate, or the corresponding monolaurate or dilaurate ormonorlcinoleate or diricinoleate. (Glyco products.) A furthersatisfactory group is the one of the cation-active emulsifying agents.Examples are the quaternary ammonium salt-s. As will be seen, the fattyalcohol su phates (for instance, Duponol ME) are also suitable for myprocess.

The examples given here below illustrate my process and my products. Ido not intend, however, to limit my products and my process to the scopeof the examples given.

In many of the examples it was decided to determine the state of thedispersed phase of the emulsions and the progress of the emulsionaggregation reaction by coagulating the emulsions or sample portionsthereof. This was done by the addition of a saturated barium chloridesolution, which coagulates the emulsions, for instance emulsions madewith- Duponol ME, with ease. The resulting coagulurn contained thedispersed phase of the emulsion, together with a small percentageof thewater.

The appearance and condition of the coagula permits to classify sameinto one of the following classes:

1. FV, fluid and viscous.

2. HV-TP, heavy, viscous but still thermoplastic.

3. IG-CF, intermediate stage, having slight gel structure, but stillshowing cold ilow characteristics.

4. NT-ST, a non-thermoplastic gel, soft and having considerable tackv(NT-ST, for non-thermoplastic, soft and tacky).

5. GD, a gel stage, dry and free or tack.

The coagula were dried at elevated temperatures, to drive out anyresidue of water and the resulting solids were classified into one ofthe above designated classes.

In -many of the examples here below, this classification was used-toexpress the state of the dispersed phase of the emulsions.

In the examples following here belowin all instances the nature of theprocess and its variables are demonstrated, instead of showing how tomake a coating composition.

It should be mentioned that in all these examples where at least stage 4(a non-thermoplastic gel) has been reached, the emulsion is an airsensitive emulsion, which can be used itself as a coating composition orwhich may be used as a component of coating compositions. (bviously,where stage 5 has been reached, the reaction is more advanced and theemulsions are suitable in coating compositions.)

COMPARATIVE EXAMPLES 1 r0 5.VARIATION or PH Wrrnour Paaoxmr: ADDITIONExample 1-Master batch In these comparative experiments a very heavilybodied linseed oil was used, which is known in the art as 0K0 M-37 oil.This product is obtained by bodying linseed oil under vacuum, has aviscosity of approximately 800 noises and has a low acid value. Asemulsifying agent 1% of Duponol ME dry was used, based on the weightofthe oil to be emulsified. Distilled water was used as dispersion mediumand the emulsion had a solid content of by weight. The emulsion was madeby adding a 10% solution of the Duponol ME to the oil and adding thewater in small portions under agitation, until a uniform emulsionresulted before the addition of the next increment of the water.

The emulsions so obtained showed satisfactory stability both in the acidand in the alkaline regions of varied pH values.

The emulsions were stirred by slow speed agitators at a temperature of60 to 65 C. 500 grams of the emulsion were used in two-liter beakers.The beakers were covered, as much as possible, even if not air-tight, toprevent excessive evaporation and what evaporation still did occur, wascompensated for by small additions of water from time to time.

It has been found that the hydrogen ion concentration has a paramountlyimportant role in the conversion process yielding air sensitiveemulsions. Studies were made in a wide range of hydrogen ionconcentration. The following three examples were in the acid region andcontained phthalete buflers.

The following preparations were made to produce emulsions with variouspH values on the acid side:

3,000 grams of the master batch emulsion of Example 1 were prepared insuch a way that it should contain the reaction product ofv 14.8

grams of phthalic anhydride and 2.0 grams NaOH, 1.2 times, dissolved inwater. The emulsion so prepared had a pH of 2.8. The followingpreparations were made with this batch:

Example 2 500 grams of the emulsion of Example 1, containing phthalatebufler as described here above, unchanged, pH 2.8.

Example 3 Example 4 500 grams of emulsion of Example 1, containingphthalate bufler as described here above, plus 1.0 gram NaOI-I, pH 5.7.

Example 5 A similar emulsion to the one of Example 1 was prepareddirectly to yield a pH of 7.1. 200 grams of M-37 oil, 20 grams of a 10%Duponol ME solution, 5.5 grams of NazHIPO4.12HzO, 780 grams of water,and 1.2 grams NaOH were used in preparing the emulsion, pH 7.1.

All the emulsions were heated to 60-65 C. and kept at that temperaturecontinuously for 96 hours, under constant agitation of approximately 45R. P. M. Samples were taken out from the emulsions at various intervalsand the same were coagulated to check the progress of the reaction.

To give a few details, it should be mentioned that the emulsion with pH2.8 reached after 16 hours a stage which was almost 4 on my scale(NT-ST) and was in between stages 4 and 5 after 96 hours. Whereas theemulsion with pH 7.1 was after 40 hours in stage 1 and reached after 96hours a point below stage 3.

The examples have shown that conversion at a pH of 7 was 'practicallynil and at a pH of 5.7 was slow. It seems that there is a veryinefiective region between a pH of 5.7 and 8.4 or in their neighborhood.

The pH of the emulsions on the acid side remained fairly constant.

It should be emphasized that to none of the emulsions dealt with in thisseries was any peroxide or per-compound added.

mai ens l3 EXAMPLE 6.-Prmoxmr: vs. No Pmaoxnm AT VARYING PH VALUES Sixportions of the master batch emulsion of Example 1 were'used in thepresent example.

, The pH of all six portions was adjusted by the addition of NaOH, to be12.2. The following were the individual characteristics of the sixportions: 6-A.-This batch was acidified and buffered with sodium acidphthalate. The pH was ad- J'usted to 2.8.

6-B.--Acidifled and buffered with sodium acid phthalate, adding 2 70 ofhydrogen peroxide based on the oil content of emulsion. The pH of thisexample was also adjusted to 2.8.

6-C'.-Acidified with sodium acid phthalate and with 2 /2% of hydrogenperoxide, based on the oil content.

In the above 6 experiments, there are actually 14 obviously have to belimited to the actual reaction conditions used in these examples.

Exmras '7 r0 10.--THE USE or METALLIC Dames In the standard way ofemulsiflcation, described in Example 1, four diiferent preparations weremade, having the following formulae:

Example 7 Grams M-3'7 linseed oil 100 10% Duponol ME solution 10Distilled water 400 KHzPO4 1 Example 8 Grams M-37 oil ...a 100Naphthenate drier 6% cobalt metal con- 20 tent 0.5

10% Duponol ME solution 10 Distilled water 400 KH2PO4 1 REMARK: Examples7 and 8 were parallel experiments, Example 8 having a metallic drierdispersed in the oil prior to emulsification.

3 parallel experiments, investigating at various Example 9 pH rangesdifferences if hydrogen peroxide is Grams used or eliminated. The totaltreatment time in M-B'l linseed oil 100 each case was 96 hours andsample quantities of 10% Duponol ME solution 10 each emulsion werecoagulated after 16 hours, 4 Distilled water 400 hours, and 96 hours ineach of the 6 indi idual Hydrochloric acid, concentrated 1 cases. These6 preparations were kept at 60 C. y to 65 C. temperatures, replacing thewater from Example 10 time to time, which evaporated. The followingGrams table summarizes the readings. M-3'7 linseed oil 100 TABLE AExample iggy pH After 16 hr. treatment 63239 1;- After-96hr. treatment2.8 (IG-CF) to (N'r-s'r'). (NT-ST)- 'r-s'r token 2.8 NT-Sl) (NT-ST)+..n.

The 6 examples of this comparative series show the followingconclusions: In the acid region the transformation is very slow near theneutrality point, fairly slow around the pH of 5.7, and somewhat fasterat the pH of 2.8. Near the neutrality Naphthenate drier 6% cobalt metalcontent 0.5 10% Duponol ME solution 10 Distilled water. 400 Concentratedhydrochloric acid 1 point around the pH of 7.2 the addition of hydrogenperoxide does not accelerate the conversion to a great extent. Thepresence of hydrogen peroxide does not show appreciable results at a pHof 5.7 either. However, at the pH range of 2.8, the addition of hydrogenperoxide is definitely accelerating the conversion.

The results permit the generalization that the hydrogen ionconcentration is of primary importance and only where'the hydrogen ionconcentration is favorable can the right eifect of hydrogen peroxide benoted. These conclusions REMARK Examples 9 and 10 were parallelexperiments,

Example 10 having a metallic drier dispersed in the oil prior toemulsiiication.

All emulsions from 7 to 10 were agitated, whi kept at temperaturesranging from 60 to 65 C., the treatment being carried out for 48 hours.Sample portions of the emulsions were coagulated after 24 hours and 48hours treatment time, using barium chloride for precipitation, and theoil products were dried at C. Table 13 shows the results of this series.

TABLE B Example Original Ccagula After 24 hours, Coagula After 48 hours,Number pH Stage Stage Almost 4. Almost (NT-ST). 34 (lrG-%F) to (NTST).

3 (IG-CF) 1-2 (FV) to (HV-TP)-.-

In the above table, where two stages are given combined with to, thismeans that the product was in between the two stages in question. Thesame applies when two numbers are combined by a hyphen. Similar systemwas used in Table A.

Table B shows, that in the-slightly acidand in the strongly acidregions, the addition of drier retarded the conversion. This retardationin the strongly acid region was more pronounced, which may be partly dueto the fact that the conversion is much more rapid in :the strongly acidregion, or in' other words, is very slow in the slightly acid region.

Examples 7 and 9 yielded after 48 hours treatment air sensitiveemulsions.

GENERAL REMARKS (a) In-my 'Patent 2,007,958. I prepared rubber-likemasses, out of bodied oils, which contained a metallic soap beforeemulsification. Such metallic soaps either were incorporated into theOils to form solidified oils, by direct addition, or the metallic soapswere formed in situ from salts, during heat bodying of the oil. Examplesof the latter alternative are carbonates, sulphides and sulphites, whichform soaps with the fatty oils at heat bodying temperatures, whileevolving CO2, or HzS, or $02 gas,

I found that where a soap (e. g. a metallic soap) is incorporated in aheat bodied oil and such an oil is used in preparing coating materials,the films obtained have reduced water resistance, apparently because thesoaps remaining in the films cause a constant swelling or evenreemulsification of the film. Therefore, in my present process I usewith preference soap-free fatty oils and obtained thereby satisfactoryweathering qualities of the films deposited from my'coating composition.

(b) The Gardner scale, used in this specification is described in detailon page 217 of the 9th edition (1939) of Physical andChemicalExamination of Paints, Varnishes, Lacquers and Colors, by Henry A.Gardner, published by the Institute of Paint and Varnish Research, 1500Rhode Island Avenue, N. W., Washington, D. C.

(c) It should be mentioned, summarizing some aspects of this invention,that in case no oxygen addition is used to bring about the emulsionaggregation, in addition to the oxygen adsorbed inthe water, theproducts so obtained are much more'durable, as they are free ofsplitting-ofi products, caused by oxidation and also free of oxidationproducts of the ester molecule. Oxidation products in general areundesirable in coating materials, as they reduce water resistance andthe life of the film.

It is of advantage if the oxygen content of the esters of my invention"does not increase during the emulsion aggregation process to an extentlarger than ,42%, when compared to the oxygen content of the ester priorto emulsification.

((1) Flat wall paints made according to my process should preferablyhave a pigment volume ratio of 35%-or more.

(e) The esters used in my emulsion aggregation process are always.thermoplastic before emulsification, which means that they are either ina fluid state at room temperature or can be reversibly fused to form aliquid.

(f) The organic solvents I may use in my process are of the type, whichare immiscible with water and which dissolve the esters and/or resinspresent in the dispersed phase of my emulsions.

(a) The air sensitive emulsions of the present process may be mixed withother emulsions, to form coating materials. Also pigments may be addedto them by grinding or by other known means, to form emulsion paint-s oremulsion enamels. It is also possible to disperse the pigments in theoil containing emulsion solids, prior to emulsification. A

(h) With regard to the question of activating the adsorbed oxygen, Iwish to recapitulate that application of heat, agitation, theapplication of vacuum, and the treatment with oscillating energy,further the use of low solid content emulsions, are the factors, whichseem to achieve this desired effect.-

(2') With rega"d to the ammonia test, I wish to mention that whereas inthe case of a positive ammonia test the starting materials for thisprocess are always sutable forthe emulsion aggregation, in most casesthe degree of bodying necessary for the emulsion aggregation process isreached earlier than the ammonia test becomes positive.

I claim:

1. The process in preparing oil-in-water type air sensitive emulsions offatty oils, which yield solid and coherent films upon demulsification,consisting of the steps of (1) bodying the fatty oil to a viscosity ofat least Q on the Gardner scale, said bodied fatty oil showing flowcharacteristics at room temperature, (2) emulsifying said bodied fattyoil in water by the aid of an emulsifying agent which is stable on theacid side of the pH range, (3) bringing the pH to a range not exceeding5.7, and (4) increasing the viscosity of the dispersed phase of theemulsion by the aid of active oxygen.

2. The process of claim 1, in which the pH of the emulsion in step (3)does not exceed 2.8.

3. The process of claim 1, in which the fatty oil is bodied to at leastY on the Gardner scale, prior to emulsification. and an oxygen evolvingcompound is used as a source of the active oxygen.

4. The process in preparing oil-in-water type air sensitive emulsions ofsoap-free bodied esters of a polyhydric alcohol formed with acids offatty oils, said esters having in a fatty acid part of the molecule morethan one double bond, said emulsion being useful in coating materials,consisting of the steps of (a) bodying the ester at least to a degreesuch that when heated to 160 C. with l sulfur an irreversible gel willform within about 4 hours, but not beyond a degree to have a bodyheavier than that which would result in conversion to an irreversiblegel in less than 15 minutes when vulcanized with /g% sulfur at 120 C.,(b) emulsifying said bodied ester in water by the aid of an emulsifyingagent which is stable on the acid side of the pH range, (0) bringing thepH of the emulsion to a range not exceeding 4, and (d) increasing theviscosity of the dispersed phase of the emulsion by the aid of an oxygenevolving compound.

5. The process of claim 4, in which the oxygen evolving compound is aperoxide.

6. The process of claim 4, in which the oxygen evolving compound ishydrogen peroxide.

'7. The process of claim 4, in which the dispersed phase of the emulsioncomprises a varnish resin, in addition 'to an ester of the fatty oiltype.

8. The process of claim 4, in which the bodied ester contentof theemulsion does not exceed 20% while step (d) is carried out.

9. The process of claim 4, in which step (d) of 17 ing from 50 C. andthe boiling point of the emulsion.

10. 'I'heprocess of claim 4, in which step (d) of the process is carriedout while the emulsion is mechanically agitated.

' 11. The process of claim 4, in which step (d) of the processis'carried out under reduced pressure.

12. The process of claim 4, in which the bodied ester is a, heat bodiedfatty oil, having drying haracteristics,

13. The process of claim 4, in which the bodied ester is a bodiedlinseed oil.

14. The process of claim 4, in which the bodied ester is a. bodied'fatty oil, having a conjugated double bond in a fatty acid constituent.

15. The process of claim 4, in which the bodied ester is an alkyd resin,comprisingin its acid component at least 50% of drying and semi-dryingfatty acids.

16. The process of claim 4, in which step (d) of the process is carriedout in a closed vessel, the

pressure in which is below that of atmospheric pressure.

17. The process of claim 4, in whichfwhile step (d) is carried out, theemulsion is treated with X-rays.

18. The process of claim 4, in which, while step (d) is carried out,'theemulsion is treated with ultra-violet rays.

' LASZLO AUER:

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

